The present disclosure relates generally to orthodontic brackets for primary teeth for patients having a combination of permanent teeth and primary teeth.
More particularly, the present disclosure relates to an orthodontic bracket for primary teeth, the orthodontic bracket being used for Phase 1 or mixed dentition interceptive treatment where patients have a mixture of primary teeth as well as permanent teeth. For many orthodontic patients, it is often necessary or desired to apply an outward force or pressure from the palatal or lingual (tongue) side of the teeth toward the facial (lip) side of the teeth in order to achieve arch width development, or to help spread the teeth outward. For instance, such outward force can be used to correct cross bites, alleviate crowding and/or other conditions where it is desirable to create or increase arch width of the top teeth, the bottom teeth, or both.
One conventional method of increasing arch width is the use of lingual expansion appliances such as a rapid palatal expander, a quadhelix system, or removable expanders. These expansion devices are located on the palatal or lingual side of the teeth. As such, these appliances can be uncomfortable for the patient as the tongue space is encroached. Having a lingual expansion appliance in the tongue space can also make speech difficult. Another problem with lingual expansion appliances is that food can become stuck between the appliances and the roof or floor of the mouth and be difficult to remove, which can potentially cause infection inside the mouth and foul odors. These appliances also typically apply a large force to the teeth so that arch development can be developed more quickly, which can be painful for the patient.
In order to help overcome the problems with lingual expansion appliances, orthodontists have begun using passive self-ligating techniques to develop arch width in patients. Passive self-ligating systems include a biased arch wire that can be used to bias or apply a gentle outward force to the teeth of a patient to develop arch width more gradually. Brackets used for passive self-ligating systems include (1) a channel for the arch wire to be received in, and (2) a movable cover to selectively enclose the arch wire. The bracket is configured such that the bracket and the tooth are movable along the arch wire, thereby allowing the teeth to gradually expand and adjust freely as the arch wire applies an outward force to the teeth. Unlike traditional braces that are bound to the wire with an elastomeric tie that creates friction on the wire, passive self-ligating brackets allow relative movement between the wire and the bracket in a reduced friction environment. Passive self-ligating techniques can provide increased comfort compared to lingual expansion appliances as all brackets in such a system can be positioned on the facial side of the teeth.
One problem associated with arch width development in Phase 1 or mixed dentition patients is that traditional brackets and passive self-ligating brackets that can potentially be placed on primary teeth typically include edgewise or rectangular channels that generally conform to the shape of a rectangular arch wire. As such, if traditional or passive-self-ligating brackets are placed on primary teeth, the rectangular channels can cause the traditional brackets to produce torque forces on the primary teeth when larger, rectangular wires that are used to expand the teeth outward twist and turn within the rectangular channels. The twisting of the large rectangular wires can potentially twist and apply a torque force on the teeth via the bracket, which can cause the primary teeth to prematurely become loose and exfoliate early, which is undesirable.
Additionally, traditional brackets and passive self-ligating brackets are designed for permanent teeth, and therefore can be larger than the facial surface of the primary teeth, which can affect the quality of the bond between the bracket and the primary teeth. Larger brackets can also affect cleanliness and hygiene of the teeth as the larger brackets encroach on a patient's gums, which can make the gum line difficult to clean, increasing the risk of gum disease.
Another problem associated with the use of traditional and passive self-ligating brackets on primary teeth is that they are relatively expensive. Primary teeth tend to fall out over time, and if an expensive bracket is placed on the primary teeth, that bracket can simply be thrown away once the primary teeth fall out, which can unnecessarily increase the cost of the treatment. Additionally, in many early treatment protocols, brackets for primary teeth are often removed after a few appointments as the brackets are temporary to support initial wires. As such, because brackets for primary teeth can be disposed of after a relatively short time, the use of more expensive passive self-ligating brackets can be an unnecessary expense.
Because of the problems associated with the use of traditional and passive self-ligating brackets on primary teeth, orthodontics have developed what is called the “2×4 method”, where for Phase 1 or mixed dentition patients, brackets are placed on the front 4 and 2 back permanent teeth, while no brackets are placed on the primary teeth. As such, the arch wire bypasses the primary teeth completely. Because the arch wire in such systems extends a significant distance without a supporting bracket, the arch wire can easily be bent or broken; for instance, when a patient chews on a hard food. Broken or bent arch wires can adversely affect the arch development of the patient and oftentimes when the arch wire is bent or broken an emergency visit is required. Broken or bent arch wires can also potentially cut or rip into a patient's cheek, gums, or lips, causing serious pain and discomfort.
What is needed then are improvements to orthodontic brackets for primary teeth.